A stealer will attach a pressure bleeding device to the master cylinder and set it going - the monkey will then raise the car on ramp and open each bleed nipple in turn and will allow an "amount" of fluid to drain into a bleeding pot.

All depends how the tech does it and how much care is taken.

A full bleed which will require diagnostic kit to be hooked up to the car which will fire the ABS solenoids etc will take far more fluid, but is rarely if ever done.